Effect of Reducing and Oxidizing Atmospheres on the PTCR Properties of BaTiO 3

BaTiO3 ceramics containing n-type dopant exhibited no PTCR effect when sintered in a reducing atmosphere. The resistivity jump of up to 3 orders of magnitude appeared after the samples were annealed in air at various temperatures. Subsequent heat treatment of the samples in a reducing atmosphere at 400°C led to a significant decrease in the resistivity jump. The PTCR effect is restored after additional annealing in air at temperatures as low as …